Fix IT tests for `GetFilesOwners`

In case when `owners.expandGroups = false` then group should be expected
in `files_approved` attribute not the specific account number.

Change-Id: I389ecb944f3088ca09a17d7a2a539a3af5786f5e

owners/src/test/java/com/googlesource/gerrit/owners/restapi/GetFilesOwnersITAbstract.java

diff --git a/owners/src/test/java/com/googlesource/gerrit/owners/restapi/GetFilesOwnersITAbstract.java b/owners/src/test/java/com/googlesource/gerrit/owners/restapi/GetFilesOwnersITAbstract.java
index 2ca419b..1633783 100644
--- a/owners/src/test/java/com/googlesource/gerrit/owners/restapi/GetFilesOwnersITAbstract.java
+++ b/owners/src/test/java/com/googlesource/gerrit/owners/restapi/GetFilesOwnersITAbstract.java
@@ -172,7 +172,7 @@
 
     assertThat(resp.value().files).isEmpty();
     assertThat(resp.value().filesApproved)
-        .containsExactly("a.txt", Sets.newHashSet(new Owner(admin.fullName(), admin.id().get())));
+        .containsExactly("a.txt", Sets.newHashSet(new GroupOwner(admin.username())));
   }
 
   @Test